For the purpose of promoting one's health, bodily exercise is taken by running or cycling. However, a person will often lose interest in such monotonous running or cycling without any measure of performance and therefore discontinue the exercise. Also, exercise is taken having little knowledge of what is proper exercise for a particular person.
Conventionally, there have not been devices which gives a person exercising an indication accurate and proper for him, for example, an indication of the number of revolutions of the pedals of a bicycle. Therefore, a limited amount of exercise will not promote health, alternatively, rather excessive exercise will result in fatigue.